In reply to Sonya Mc:
in the short term can tesco barr services from this number to your phone?
there's a few things that might have happened. althought he number is new to you, it might have previosuly been used by someone else.
it's also possible someone naughty has registered your phone for you (before you got it for example) the company could also just be trying it on and finally there's that walware discussed above.
i can tell you how i get to the settings, but i don't know how similar your menus will be if that helpes at all?
from the main home screen click on applications and find the settings icon, click that and locate another applications icon
on mine, the unknown sources is at the top of the list (make sure it's unticked)
next down is manage applications
here i have "tabs" across the top, the first one being downloaded
pick on of the games you've installed eg solitare
scroll down and the last section is permissions
here for example the solitare i've installed has permission to modify delete storage (so it can install itself and save configuration i'm guessing)
it also wants permission to read phone status and ID (not sure about the ID, but i assume the phone status is so it knows when a call comes in?)
so visit all three of those games you've installed and see if any of them have permission to send texts
HTH's
PS i'm going to chekc my first orange bill for this exact same thing now too